This invention relates to the field of magnetic circuits for electronic devices, particularly to the adaptation and application of permanent magnets rather than electromagnets in applications for such devices and, more particularly, to a unique magnetic circuit which provides for the establishment, maintenance, and control, of an axially extending electromagnetic field of annular configuration viewed cross sectionally.
The utilization of permanent magnet devices and structures to replace electromagnetic type yokes in electronic devices, cathode ray tubes for instance, has received significant acceptance in the electronics industry. To achieve the proper operation of electron beam type devices it is most times necessary to apply a magnetic field having its flux lines parallel to the longitudinal axis of travel path of the electrons being controlled. Quite frequently, this space assumes the shape of a long cylinder and the flux lines to be developed parallel to the axis of such a cylinder have been conventionally produced for many years by shielded solenoids. Such solenoids require extremely critical power regulation, and if the field strength is of a significant magnitude, cooling may be required. The power and cooling requirements of such electromagnetic and solenoid type devices have been advantageously replaced by the present day developments in the use of permanent magnet structures to produce the controlling longitudinally extending linear flux fields for the control of these electron beam flows.
Various prior art devices have contributed to the development of the technology in this area. For example, the U.S. Pat. No. 3,768,054, to Neugebauer, entitled "Low Flux Leakage Magnetic Construction", teaches a number of magnetic circuits utilizing magnetic cladding means to reduce exterior flux leakage and increase the controlled magnetic field intensity. The advantageous features of this and similar devices are, significantly, the reduction of flux loss and very effective control without any increase, in fact most time a decrease, in the size or weight of the magnetic circuit elements.
In my own copending application Ser. No. 685,426, filed Dec. 24, 1984, entitled "Lightweight Cladding for Magnetic Circuits", I disclose and claim the advantageous features of certain magnetic structures arranged with flux fields transverse to each other and with tapered thicknesses of the restraining cladding magnetic elements in order to effectively control and maintain the linearity and constancy of the working flux in the flux spaces of such devices.
In all of the prior art there appears to be, even in the most recent developments, the control of axially extending magnetic flux fields through cross sectional areas which are complete and uninterrupted, that is to say in the form of squares, rectangles, circles and the like geometric shapes.
With the attainment of greater advances in the art some devices that have been developed, while having axial symmetry, require magnetic fields within only short distances from their peripheries. In such configurations, the provision of a magnetic field over the entire interior would require unnecessarily massive and bulky components, and be unduly prodigal of magnetic material.
With this, then, being the state of the art, I conceived and developed in the present invention to provide for the control of linearily extending flux fields in an annular cross section axially extending permanent magnet structure.
It is a primary object of the present invention to provide for the development and control of axially extending magnetic flux fields in annular shaped spaces, that is to say, shell-like tubular cylindrical elements having inner and outer shells between which the flux field obtains, said flux field being maintained constant or controllably varied, as desired, in accordance with the particular cladding and arrangement of permanent magnet structures in the combination.
It is, additionally, an object of this invention to provide for the control of axially extending longitudinal magnetic flux fields by the application of varying or tapered thickness type permanent magnetic structures arranged and disposed along the length of the device, and oriented with the magnetic flux therein transverse to the flux of the magnetic element which produces the axially extending field.
A still further object of the invention is to provide a permanent magnet electronic control device which can furnish an axially extending controllable magnetic flux field with minimal weight and space requirements, optimum economy of magnetic materials, and which requires no external power.
These and other objects and features of the invention will become the more readily apparent in the light of the ensuing detailed disclosure, particularly in the light of the drawing, which is a sectional-elevational view taken through a permanent magnet device according to the present invention.